1. Field of the Invention
The present invention relates to an image forming apparatus and a head drive control method.
2. Description of the Related Art
As one type of image forming apparatuses, such as printers, facsimile machines, copiers, plotters, or multifunction peripherals (MFP) having functions of these devices, an image forming apparatus employing a liquid-ejection recording method is known, such as an inkjet recording apparatus that uses, as a recording head, a liquid ejection head to eject droplets.
In the image forming apparatuses as described above, there is a known apparatus including a head drive control device that generates a drive waveform of multiple time-series drive pulses, selects a single or multiple drive pulses from the drive waveform according to the size of a droplet, and applies the selected pulses to a pressure generator.
Conventionally, there is a known apparatus that generates a pulse as a drive pulse for ejecting dummy droplets. Specifically, a pulse is generated such that a potential of a pull-in waveform element (expansion waveform element) is reduced from a reference potential by a certain voltage in order to expand a pressurized liquid chamber to pull in the meniscus of a liquid in the nozzle, and a predetermined hold state is maintained. Subsequently, a potential of a pressurizing waveform element (contraction waveform element) is increased by a certain voltage in order to contract the pressurized liquid chamber to eject a droplet, and a predetermined hold state is maintained. Thereafter, the potential of the pull-in waveform element (expansion waveform element) is reduced again in order to expand the pressurized liquid chamber to tear off a portion of the droplet being ejected and to return a remaining portion to the inside of the nozzle, and a predetermined hold state is maintained. Subsequently, the potential of the pressurizing waveform element (contraction waveform element) is increased to return the pressurized liquid chamber to the initial state (at this time, by setting the slope of the waveform element to be moderate, droplets are not ejected) (Japanese Patent Application Laid-open No. 2008-149703).
Incidentally, in the image forming apparatus employing the liquid ejection method, there is a need to reduce generation of mist due to droplet ejection and to enable high-frequency driving.
Therefore, it is desirable to reduce generation of mist due to droplet ejection and to enable high-frequency driving.